Revert "Allow deprecation warning for the return_200_for_cluster_health_timeout parameter (#80178) (#80444)"

This reverts commit 4102cf7.

Author: arteam

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/cluster.health/20_request_timeout.yml

@@ -41,10 +41,7 @@
   - skip:
       version: " - 7.15.99"
       reason: "return_200_for_cluster_health_timeout was added in 7.16"
-      features: [ "allowed_warnings" ]
   - do:
-      allowed_warnings:
-        - 'the [return_200_for_cluster_health_timeout] parameter is deprecated and will be removed in a future release.'
       cluster.health:
         timeout: 1ms
         wait_for_active_shards: 5